1. Field of the Invention
This invention relates to a room temperature rapid-curable silicone composition which has a superior storage stability, and also is rapid-curable upon mere blending, becomes an elastic body having superior heat resistance, moisture resistance and water-exposure adhesive properties and is preferably usable as a sealant for various electric and electronic parts and common constructional joints, as an oil seal for automobiles and also as a coating material required to have follow-up properties.
2. Description of the Prior Art
In recent years, in the market for silicone, room temperature rapid-curable materials of a two-part or three-part type have increasingly become important for the purpose of the rationalization of operation.
Room temperature rapid-curable silicone materials conventionally used include addition reaction curable materials, condensation rapid-curable materials and amine-ketone dehydration condensation curable materials. However, in the case of the addition reaction curable materials, platinum catalysts may be poisoned by any impurities on substrate surfaces to cause curing inhibition which provides an obstacle, and hence the materials can not be expected to be applicable to a wide range of substrates. In the case of the condensation rapid-curable materials, water necessary for curing is brought in the form of an emulsion or the like, and hence they have critical disadvantages that their curability may vary with time and, in the worst case, they may separate. Also, in the case of a ketimine and water-producing material based on an amine-ketone reaction as reported in Japanese Laid-open Publication (Kokai) No. 5-279570, materials generally good in respect of curability and storage stability are obtainable, but especially an irritating odor due to the amine compound and a corrosive action on substrates come into question. Hence, such materials may be limited to some operation and use.
The present invention was made in order to improve the above circumstances. Accordingly, an object of the present invention is to provide a room temperature rapid-curable silicone composition having superior curability, durability and storage stability while sufficiently exhibiting properties inherent in silicone compositions.
As a result of extensive studies made in order to achieve the above object, the present inventors have discovered that the use of a composition comprised basically of an organopolysiloxane, a hydrolyzable silane and a water-containing wet-process silica makes it possible to obtain a composition having a good rapid-curability, being completely deep-curable and adhesive without regard to materials of substrates and also having very superior storage stability. They have also discovered that this composition has properties such as sealing properties, substrate follow-up properties and dust-proofing properties and can furnish a cured product having superior general physical properties such as various electrical properties and mechanical properties. Thus, they have accomplished the present invention.
Accordingly, the present invention provides a room temperature rapid-curable silicone composition making use of a wet-process silica as a chief source for feeding water necessary for condensation curing reaction.
More specifically, the silicone composition of the present invention is a room temperature rapid-curable silicone composition comprising:
(A) 100 parts by weight of an organopolysiloxane terminated with hydroxyl groups, having a viscosity of from 25 mPaxc2x7s to 1,000,000 mPaxc2x7s at 25xc2x0 C.;
(B) from 2 parts by weight to 50 parts by weight of at least one compound selected from the group consisting of a hydrolyzable silane represented by the following general formula (1):
RnSiX4xe2x88x92nxe2x80x83xe2x80x83(1)
wherein R may be the same or different when it is in plurality, and represents a monovalent hydrocarbon group having 1 to 12 carbon atoms; X represents at least one group selected from the group consisting of a ketoxime group, an alkoxyl group, an alkenoxyl group and an acyloxyl group; and n represents an integer of 0 to 2, and a partial hydrolysis-condensation product thereof; and
(C) from 3 parts by weight to 200 parts by weight of a water-containing wet-process silica having an average particle diameter of 100 xcexcm or smaller; the component (C) being a chief source for feeding water necessary for condensation curing reaction.